Unusual stuffing for a recipe (4)
I believe the answer is:
rare
'unusual' is the definition.
(rare can mean unusual or odd)
'stuffing for a recipe' is the wordplay.
'stuffing' indicates the answer is hidden within the clue.
'RARE' can be found hidden inside 'for a recipe'.
(Other definitions for rare that I've seen before include "Exceptional" , "Special" , "Occurring infrequently" , "Rear up, being scarce" , "not often spotted" .)